In the modern era, there has been an explosion of information in nearly all fields of endeavor. There has not, however, been a corresponding revolution in apparatus and techniques for teaching, learning, assimilating and organizing information.
Commonly employed techniques in education employ lectures, notes, textbooks, laboratory exercises and audio-visual aids. All of these have severe disadvantages. Textbooks are normally organized according to topics and present, in each chapter or section, a detailed body of knowledge relating to the entire topic. Normally, the amount of specific information contained in a textbook relating to a specific topic is more than can be assimilated in a given reading. The internal organization of the information contained in a given section and relating to a given topic is often far from clear. The use of a standard outline in association with a textbook aids in the organization of the material but does not eliminate the need for the student to classify the textbook material according to the outline or the monotony or dealing with pages of information which are presented in an unclassified manner. A further important difficulty is the inability of the student to define the level of detail which he can effectively assimilate in a given study situation and to limit his efforts to the given level of detail. It follows that after a given study time, the student will have mastered some topics in great depth and other topics not at all.
Lectures, notes and laboratory exercises are normally directed at particular points of interest or difficulty and do not give an overview of the entire body of information to be mastered, so as to put these points in perspective.
Audio-visual aids have been developed in recent years, typically in combination with microfilm or computer displays and terminals for enabling individualized learning. While these do represent a significant advance in the organization of information and the completeness of presentation, they suffer from the disadvantage that their use is limited to suitable facilities which are not always available to a student at all locations at which study may take place.